Australian world champion Casey Stoner, riding with a pain-killing injection due to his fractured right ankle and torn ligaments, finished fourth.

It was Pedrosa's 17th career victory and puts him on 207 points in the world championship standings, 18 points behind Lorenzo.

"It was a good weekend. I think the bike was working well. We were spinning all of practice, but we had a good feeling. So today for the race I was confident," Pedrosa told reporters.

Pedrosa started on pole but was challenged in an eventful race that saw Ben Spies take control in the opening laps before the American's hopes ended with 22 laps remaining when his engine blew forcing him to pull off the track.

Pedrosa had a scare of his own when his bike wobbled with 12 laps to go and ran into the grass, but he soon recovered.

"When I shifted again to first, the bike had a good kick on me and yeah, I almost lost control," Pedrosa said. "But I kept the bike on the track. I lost one second on that lap."

Stoner fought through the pain of his injuries to finish fourth having only been declared fit to race on Sunday morning.

In qualifying on Saturday the twice world champion was thrown off his bike and rolled across the grass.

He tried to walk off the track but had to call for medical attention and was taken away on a stretcher.